1. Field of the Invention
The present invention relates to a multiple channel earphone, and more particularly, to a multiple channel earphone having an extended sound field.
2. Description of the Related Art
Along with continuous progress of digital technology, the entertainment of the ordinary people had been gradually digitalized. For example, the DVD (Digital Video Disc, also known as Digital Versatile Disc) player is very popular in many households nowadays. Since DVD player has basically provided decoding functions such as Dolby Digital or Digital Theater System (DTS), it is capable of decoding digital signals and outputting analog signals to the speakers.
The multiple channel speaker is an inevitable device for enjoying the high quality digital AV entertainment program, and the 5.1 channel speaker is a fundamental component of the multiple channel speaker.
FIG. 1 schematically shows a diagram of a home theater with a 5.1 channel speaker. Referring to FIG. 1, when the DVD player 100 is playing an AV program, the DVD player 100 provides different audio signals to a front left speaker 102a and a front right speaker 102b, a center speaker 104, a left surround speaker 106a and a right surround speaker 106b, and a subwoofer 108, so as to create a 3D spatial sound effect for providing a realistic setting for the listener.
However, it is required to use an earphone to listen music under the circumstance of not suitable for using the speaker (for example, using speaker may disturb others). Referring to FIG. 2A, since a typical earphone 200a only has one speaker 210 in its both sides, respectively, it is not possible for the listener to enjoy the multiple channel sound effect provided by the DVD player.
Therefore, an earphone having a plurality of speakers in its main body had been proposed in the prior art. The conventional earphone 200b has a main channel speaker 202, a center speaker 204, and a surround speaker 206 in its both sides, respectively. By cooperated with a special design plug 208, the DVD player provides different channel's audio signal to different speaker through the plug 208, so as to further create the spatial sound effect of the 5.1 channel speaker in home theater environment. Since the delaying output of the audio signal is controlled in a digital way (e.g. with a circuit design) in the conventional earphone 200b, the spatial sound effect provided by it is not so good. It is far behind when compared with the spatial sound effect provided by the 5.1 channel speaker in home theater environment as shown in FIG. 1, and it cannot present the quality and function of the multiple channel surrounding sound effect.